Although processing power and storage capacities have increased beyond all recognition since the first introduction of microprocessors in the 1970s the underlying technology of microcomputers and their operations have remained basically the same. An important element of this underlying operation is the serial presence detect (SPD) performed when a microprocessor or microcomputer is booted (started or restarted). SPD is information stored in a RAM memory module that tells the microcomputer's basic input/output system (BIOS) the module's size, data width, speed, and voltage. The BIOS uses this information to configure the memory properly for reliability and performance. If a memory module does not have SPD, the BIOS assumes the memory module's information. Sometimes this is not problematic but other times, as is common with SDRAM memory, the computer may not boot at all or, when it does boot, the assumed information may cause fatal exception errors.
As such integrated circuits (ICs) have been developed to access the SPD information within RAM memory modules and, as with many integrated circuit technologies, there is commercial benefit of integrating additional functionality within the overall microcomputer into the same semiconductor die as that performing the SPD process. It is therefore common for such SPD circuits to be integrated with a self-contained temperature sensor. This provides advantages such as reduced component count, reduced inventory, smaller microcomputer footprint, and reduced cost. However, the resulting integrated circuit has increased power consumption which whilst not critical for motherboard applications within PCs, is a critical aspect for designers of microcomputers intended for handheld, portable, and remote applications wherein their power is derived primarily from battery modules. Alternatively, employing the IC as part of a common platform for lower manufacturing costs and standardization also suffers the disadvantage of increased power consumption as often all supplied variants of the common platform do not require the full IC functionality.
Adjusting power consumption in the vast majority of prior art multi-function ICs is performed by providing control signaling to the integrated circuit instructing it as to which portions of the IC should be powered and which un-powered. However, in prior art instances of integrated circuits it is common for portions of the IC to be left permanently powered as they are common to more than a single function, for example within an integrated SPD and temperature sensing circuit the oscillator remains powered despite being a major portion of the overall power consumption of the circuit since it is used to produce clocking to access memory within the integrated circuit and by the temperature sensing circuit.
It would be advantageous to overcome some of the aforementioned drawbacks of the prior art.